How to Choose the Right Air Filter

February 17, 2016

Selecting the right HVAC air filter for your home can often be a confusing process, with so many products available in the market. Being able to choose the best air filter takes a basic understanding of MERV ratings (Minimum Efficiency Reporting Value), and how they reflect the quality of the filter.

An air filter’s MERV indicates its ability to capture airborne particles while air is flowing through your heating or cooling system. For residential purposes, MERV ratings range from 1-12. Generally speaking, the cheaper the filter is, the lower the MERV number is. Air filters with lower MERV ratings will remove a smaller percentage of pollutants from your home. Listed below are some of the most common types of residential HVAC air filters, and the MERV rating you can expect to find on each one:

Fiberglass Air Filters

Often available for less than $10, fiberglass air filters will only remove larger particles like dust, lint and small insects. Originally designed to protect heating and air conditioning equipment, these filters are less effective when it comes to improving indoor air quality. It’s recommended to replace them once every month.

MERV Rating: 1-4

Electrostatic Air Filters

Disposable electrostatic air filters contain self-charging electrostatic cotton or paper fibers that attract and trap small particles. These filters are good for homes with children, pets or smokers, and are affordable in standard sizes. It is recommended to replace disposable electrostatic filters every three months to keep your home free of airborne allergens.

MERV Rating: 6-8

Pleated Air Filters

A step up from fiberglass air filters and more popular than electrostatic air filters, disposable pleated filters capture between 25-45% percent of the airborne pollutants in your home. Made from polyester or cotton paper, their pleated design allows them to capture particles down to three microns in size without significantly inhibiting airflow. Pleated air filters can be purchased for around $15 each, and like electrostatic air filters, only need to be switched out every three months.

MERV Rating: 8-13

High-efficiency Air Filters

High-efficiency air filters are the most effective filters for most residential HVAC systems. Made from 4-5” pleated synthetic cotton attached to a rigid metal grid, these filters can trap up to 85 percent of very tiny dust particles, pollen, mold and other irritants.

Remember that for residential purposes, 12 is the highest MERV rating possible. Acquiring an HVAC filter ranging between a 9-12 MERV rating is an excellent means of controlling dust and other particles.

MERV Rating: 9-16

Another important aspect to consider when choosing a filter is airflow restriction or static pressure drop across the filter. Generally filters with a higher MERV rating have a more profound effect on airflow. Having high static pressure will cause your HVAC system to work harder, and can lead to system failures.